Topic: Flat belly questions

[yota-tota]

I got my MC07 R10 adapter last week and going to try and get a complete flat belly on my 91 x-cab. Thing is this is my daily driver and when i swap the duals in over a weekend i probably wont have enough time to make up a new tunnel to drive it to work Monday morning.

So bascily how much flex would there be in the floor with some of the tunnel cut out? My cab and floor are all solid with no rust, i would just like to be able to mount my seats and drive to work and stuff without worrying about the floor sagging in horribly if i hit a pot hole    Oh and not sure how much i would need to cut as well, i was reading a couple posts where the guy cut the crap out of the tunnel to the floor and another where it was only the top section yet still was flat on the bottom or close to it. Fews pics would be nice 

[snowshoebrue]

with mine i just cut the top off then lifted it up to see where it hit then lowered it down and cut that out.   as long as you dont cut the whole cab front to back you shouldn't have issues with your floors flexing out.

[RynothealbinO]

I know when I did mine I cut out the bare minimum of what had to be cut, and it was still quite a bit.  Since it was my daily driver I had to mount the seats back in and drive it.  I did not notice any flex at all with the tunnel cut out. Until I got the tunnel back in I just put a cut out section of my plastic inner fender (since I dont run fenders lol) over the U-joint.  As far as what had to be cut out, there were some areas where it would not be a whole lot, but there are a few where the housing juts out and you need to make the tunnel go wider.  One area I know was on the front seat mounts.  I had to cut a notch out right at the inside adge of the front mount, bend the tunnel out more, and then reweld them to each other.  From what I remember, if you didn't go for a true flat belly, but setled for 2 or 3 inches of lift, you would have to cut out ALOT less.  I have a single case and I am pretty sure I could have got out 3 inches of lift by only cutting the hole where the shift boot mounts a little larger.  Another thing to watch out for is the speedo cable.  I notched my floor pan for it, and it still over flexed and broke after 20 or so miles, so you might want to consider taking a large notch that allows the cable to flow naturally instead of forcing anything.  I hope that helps.

[yota-tota [OP]]

Thanks for info dude! Where I have the R10 adapter I read that it only takes about 3inches of drivetrain lift to get it flat. I'm going to run a UHMW skid off the side of my F.R.O.R. style mount so aslong as the bottom of it is an inch of so I'd be happy.

Just glad that I don't need to worry about the floor caving in without having the tunnel inplace. 

[85runner_]

I am in the proccess of lifting the drivetrain as well. One question I have is do you need to lift the motor mounts as well or are you just tiping the rear cases up?

Thanx
Paul

[RynothealbinO]

The "proper" way to do it is to raise the engine moints also, so the engine stays at about the same angle.  When I did mine I just raised the rear...which is why my rear drive shaft now hates me.  If you go this route you may need to ship your axles to correct for driveline angles, or switch to a CV style shaft, but you may need a new shaft anyways because of the length thing, so that is not such a huge deal.  Righ now mine has no lift, but a flatbelly and stock driveshafts and both are barely hanging onto life.  This summer it is getting Chevies, RUF's, square front shaft, and homemade CV rear shaft made out of a front CV section and the stock rear section.  Another thing to keep in mind is that alot of these guys who have flatbellys also have body lifts, so they are able to get away with a lot less cutting and being able to raise the front mounts more if they go that route without hitting the hood.  I hope that helps.

[KYOTA]

the motor mounts will twist enough. they dont really move that much anyway, picture lifting a pencil up like an inch off the desk from one end, the end thats still resting on the desk doesnt pivot much compared to the lift of the rear. check your fan after the lift, I had to trim the shroud a little bit on top ( 1/4" )

[TheCookieMonster]

so i did a flatbelly on my truck not to long ago. have any of you noticed bad tranny noises after you did it?? its not too bad in 1st and 2nd gear but once you get going over 30-35 mph it starts grinding and making some interesting noises? its really bad when your in 4-5 gear and put the trans in neutral ? im pretty sure its beacause the angle of the trans because it never did it before the flatbelly? have you guys noticed this at all, or have any input??

back on topic 

i cut my tunnel out from the front to the back of the cab. if you do that the floor is pretty floppy. if you just cut the top of the tunnel out it would probably have enough strenght to hold. just depends on how much you 

[BLACKDOG]

Most of the guys that I've seen do flat bellies cut out the whole floor, and then frame it in, and reinstall it, and recover the tunnel.  This gives the whole bottom of the cab a lot more support than just cutting out and reinstalling the tunnel. 


The angle of the transmission with or without a flat belly shouldn't make a huge difference,  I've got a feeling its a coincidence.  The only reason I could see for that is if you've got some slop in the transmission or in the mating of the transmission to the motor, and t-case to transmission.  I'm just guessing on that one.  But if you think about it, it shouldn't matter what angle the transmission is at (within reason)  it didn't grind when going uphill did it?  thats an angle change as well, and a more significant one than doing a flatbelly.

[tryn2Crawl]

For me. I layed off the   's and do sit ups.Have a workout a plan and stick to it

[85runner_]

I have no body lift am going to achive flat belly. I am planning on cutting up the floor and re-structuring as nessesary.

[RynothealbinO]

Mine makes a horrible grinding noise like yours Cookie Monster.  Mine usually only did it in 4th and 5th though.  To check it out I put the truck in the garage, rear axle jacked up, blocked, back tires off and had my dad row through the gears while I was underneath.  From the best of what I can tell it is coming from the U-Joint on the driveshaft.  I plan on making a CV style one to replace it this spring though, so hopefully that will solve the problem.  That is another reason for raising the front mounts, becase it gets the driveline angles closer to stock.  What do you have for a rear driveshaft?

[Hyena]

its your rear driveline angle.  some people get that when going to duals also because the angle changes.  i have heard putting a cv in helps.  i got a flet belly on mine with no body lift and no noises though.  i had to cut a hell of a lot out of the floor.

[TheCookieMonster]

im running the stock driveline in the rear with no cv. that seems like the problem. thanks for the input guys